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Initial revision

/*	$OpenBSD: clock.c,v 1.1 2005/04/19 21:30:18 miod Exp $	*/
/*	OpenBSD: clock.c,v 1.19 2004/04/08 01:11:21 deraadt Exp 	*/

/*
 * Copyright (c) 1992, 1993
 *	The Regents of the University of California.  All rights reserved.
 * Copyright (c) 1994 Gordon W. Ross
 * Copyright (c) 1993 Adam Glass
 * Copyright (c) 1996 Paul Kranenburg
 * Copyright (c) 1996
 * 	The President and Fellows of Harvard College. All rights reserved.
 *
 * This software was developed by the Computer Systems Engineering group
 * at Lawrence Berkeley Laboratory under DARPA contract BG 91-66 and
 * contributed to Berkeley.
 *
 * All advertising materials mentioning features or use of this software
 * must display the following acknowledgement:
 *	This product includes software developed by Harvard University.
 *	This product includes software developed by the University of
 *	California, Lawrence Berkeley Laboratory.
 *
 * Redistribution and use in source and binary forms, with or without
 * modification, are permitted provided that the following conditions
 * are met:
 *
 * 1. Redistributions of source code must retain the above copyright
 *    notice, this list of conditions and the following disclaimer.
 * 2. Redistributions in binary form must reproduce the above copyright
 *    notice, this list of conditions and the following disclaimer in the
 *    documentation and/or other materials provided with the distribution.
 * 3. All advertising materials mentioning features or use of this software
 *    must display the following acknowledgement:
 *	This product includes software developed by the University of
 *	California, Berkeley and its contributors.
 *	This product includes software developed by Paul Kranenburg.
 *	This product includes software developed by Harvard University.
 * 4. Neither the name of the University nor the names of its contributors
 *    may be used to endorse or promote products derived from this software
 *    without specific prior written permission.
 *
 * THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
 * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
 * ARE DISCLAIMED.  IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
 * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
 * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
 * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
 * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
 * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
 * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
 * SUCH DAMAGE.
 *
 *	@(#)clock.c	8.1 (Berkeley) 6/11/93
 *
 */

/*
 * Clock driver.  This is the id prom and eeprom driver as well
 * and includes the timer register functions too.
 */

#include <sys/param.h>
#include <sys/kernel.h>
#include <sys/device.h>
#include <sys/systm.h>

#include <uvm/uvm_extern.h>

#include <machine/autoconf.h>
#include <machine/cpu.h>

#include <sparc/sparc/asm.h>
#include <machine/idt.h>
#include <machine/kap.h>

/*
 * Statistics clock interval and variance, in usec.  Variance must be a
 * power of two.  Since this gives us an even number, not an odd number,
 * we discard one case and compensate.  That is, a variance of 1024 would
 * give us offsets in [0..1023].  Instead, we take offsets in [1..1023].
 * This is symmetric about the point 512, or statvar/2, and thus averages
 * to that value (assuming uniform random numbers).
 */
/* XXX fix comment to match value */
int statvar = 8192;
int statmin;			/* statclock interval - 1/2*variance */

int timerblurb = 10; /* Guess a value; used before clock is attached */

/*
 * Set up the real-time and statistics clocks.  Leave stathz 0 only if
 * no alternative timer is available.
 *
 * The frequencies of these clocks must be an even number of microseconds.
 */
void
cpu_initclocks()
{
	profhz = hz;
	tick = 1000000 / hz;
}

/*
 * Dummy setstatclockrate(), since we know profhz==hz.
 */
/* ARGSUSED */
void
setstatclockrate(newhz)
	int newhz;
{
	/* nothing */
}

/*
 * Level 10 (clock) interrupts.
 */
int
clockintr(cap)
	void *cap;
{
	hardclock((struct clockframe *)cap);

	return (1);
}

/*
 * Level 14 (stat clock) interrupt handler.
 */
int
statintr(cap)
	void *cap;
{
#if 1
	panic("level 14 interrupt");
#else
	statclock((struct clockframe *)cap);
#endif

	return (1);
}

/*
 * Return the best possible estimate of the time in the timeval
 * to which tvp points.  We do this by returning the current time
 * plus the amount of time since the last clock interrupt.
 *
 * Check that this time is no less than any previously-reported time,
 * which could happen around the time of a clock adjustment.  Just for
 * fun, we guarantee that the time will be greater than the value
 * obtained by a previous call.
 */
void
microtime(tvp)
	struct timeval *tvp;
{
	int s;
	static struct timeval lasttime;
	static struct timeval oneusec = {0, 1};

	s = splhigh();
	*tvp = time;
	splx(s);

	if (timercmp(tvp, &lasttime, <=))
		timeradd(&lasttime, &oneusec, tvp);

	lasttime = *tvp;
}